Abstract: Disclosed herein is a rectifier circuit for receiving an AC signal from a receiver coil in an inductive power transfer system. The circuit is configured to operate at an operating frequency. The circuit comprises a Class-E rectifier; an AC signal supplier configured to supply an AC signal to the rectifier circuit; and a resonant network having an inductor and a capacitor. The resonant network has a resonant frequency, and the ratio of the resonant frequency to the operating frequency is within the range of 1.75 to 3.

Abstract: Embodiments described herein relate to a driving circuit, comprising: a rectification stage configured to convert an AC input to a rectified AC output; a transmitter coil; and an inverter directly coupled to the rectification stage. The rectified AC output from the rectification stage is fed directly to the inverter and the inverter is configured to convert the rectified AC output from the rectifier to an AC output for the transmitter coil.

Abstract: The present disclosure relates to a wireless power transmission system (100) comprising a wireless power transmission device (108), and a method of identifying the presence of a foreign object within wireless power transmission range of the wireless power transmission device (108). The wireless power transmission system (100) comprises a wireless power transmission device (108) for wirelessly transmitting power to an electronic receiver device (102) and a digital subsystem comprising an analog to digital converter “ADC” and a processor. The ADC is configured to digitise a waveform associated with the wireless power transmission device (108), to produce a source-drain waveform vector. The processor is configured to apply a classifier to the source-drain waveform vector; and determine, based on a numerical output of the classifier, whether a foreign object is present within wireless power transmission range of the wireless power transmission device (108).

Abstract: A system for synthesising inertia in exercise equipment, the exercise equipment comprising a rotatable member to which a user applies a user torque in use, the system comprising: an electric drive system comprising an electric motor operably connected to the rotatable member, the electric motor configured to impart a resistance torque, in use, on the rotatable member of the exercise equipment, whereby the resistance torque opposes the user torque; at least one sensor for monitoring a user input to the rotatable member; and a control system, comprising at least a processor and a memory, wherein the control system is connected to the at least one sensor and is configured to use the input from the at least one sensor and at least one predetermined parameter storable in the memory, to determine a resistance torque and to provide instructions to the electric drive mechanism to impart said resistance torque on said rotatable member.

Abstract: Disclosed herein is a rectifier circuit for receiving an AC signal from a receiver coil in an inductive power transfer system. The circuit is configured to operate at an operating frequency. The circuit comprises a Class-E rectifier; an AC signal supplier configured to supply an AC signal to the rectifier circuit; and a resonant network having an inductor and a capacitor. The resonant network has a resonant frequency, and the ratio of the resonant frequency to the operating frequency is within the range of 1.75 to 3.

Abstract: A load-independent Class EF inverter may maintain ZVS operation, and produce a constant output current, rather than a constant output voltage, regardless of the load resistance. A constant output current allows the inverter to operate efficiently for a load range from zero resistance (short circuit) to a certain maximum load resistance, making the inverter more suitable as a coil driver for an IPT system. The resonant frequency of the resonant circuit may be tuned to a non-integer multiple of a switching frequency.

Abstract: A system for synthesising inertia in exercise equipment, the exercise equipment comprising a rotatable member to which a user applies a user torque in use, the system comprising: an electric drive system comprising an electric motor operably connected to the rotatable member, the electric motor configured to impart a resistance torque, in use, on the rotatable member of the exercise equipment, whereby the resistance torque opposes the user torque; at least one sensor for monitoring a user input to the rotatable member; and a control system, comprising at least a processor and a memory, wherein the control system is connected to the at least one sensor and is configured to use the input from the at least one sensor and at least one predetermined parameter storable in the memory, to determine a resistance torque and to provide instructions to the electric drive mechanism to impart said resistance torque on said rotatable member.

Abstract: An inductive power transfer system comprises a transmitter circuit comprising a transmitter coil and a receiver circuit comprising a receiver coil spaced from the transmitter coil. The transmitter circuit is in the form of a Class E amplifier with a first inductor and a transistor in series between the terminals of a power supply. A first transmitter capacitance is in parallel with the transistor between the first inductor and a power supply terminal, a primary tank circuit in parallel with the first transmitter capacitance, the primary tank circuit comprising the transmitter coil and a second transmitter capacitance arranged in parallel with the transmitter coil, and a third transmitter capacitance in series with the first inductor between the first transmitter capacitance and the primary tank circuit. The second transmitter capacitance is selected such that a resonant frequency of the primary tank circuit is not equal to the first frequency.

Abstract: A load-independent Class EF inverter may maintain ZVS operation, and produce a constant output current, rather than a constant output voltage, regardless of the load resistance. A constant output current allows the inverter to operate efficiently for a load range from zero resistance (short circuit) to a certain maximum load resistance, making the inverter more suitable as a coil driver for an IPT system. The resonant frequency of the resonant circuit may be tuned to a non-integer multiple of a switching frequency.

Abstract: There is provided a near-field inductive power transfer system (10), comprising a power transmission device (100) arranged to transmit power wirelessly at a first frequency, f0, and a power reception device (200) arranged to receive power transmitted by the power transmission device (100). The power reception device (200) is moveable relative to the power transmission device (100) and comprises a receiver circuit (210) configured to receive power for powering a variable load (230) when the power reception device (200) is in a near-field region of the power transmission device (100), the receiver circuit being a resonant circuit with a resonant frequency, fR, such that 0.2<f0/fR<3.

Abstract: An inductive power transfer system comprises a transmitter coil TX and a receiver coil RX spaced from the transmitter coil. A transmitter circuit comprises the transmitter coil and is in the form of a Class E amplifier with a first inductor Uchoke and a transistor in series between the terminals of a power supply, a first transmitter capacitor Cpar in parallel with the transistor between the first inductor and a power supply terminal, a primary tank circuit in parallel with the first transmitter capacitor, the primary tank circuit comprising the transmitter coil and a second transmitter capacitor Cres arranged in parallel with the transmitter coil, and a third transmitter capacitor Cser in series with the first inductor between the first transmitter capacitor and the primary tank circuit.

Abstract: A method for monitoring the condition of at least one cell of a battery, used in an electric or hybrid electric vehicle. The battery is connected to a power converter to supply electrical power to an electrical load. The method includes the steps of: controlling the power converter to vary the input impedance of the power converter to draw a varying current from the cell; sensing the voltage across the cell and the current drawn in response to varying the impedance of the power converter; calculating from the sensed voltage and current the complex impedance of the cell; and comparing the calculated complex impedance with information indicative of a correlation between (i) the complex impedance and (ii) information indicative of the condition of the cell, to give an indication of the condition of the cell. The varying current may be actively varied or passively varied.